This invention relates generally to computed tomography (CT) imaging and more particularly, to generating depth information scout images.
In at least one known computed tomography (CT) imaging system configuration, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as the xe2x80x9cimaging planexe2x80x9d. The x-ray beam passes through the object being imaged, such as a patient. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam attenuation at the detector location. The attenuation measurements from all the detectors are acquired separately to produce a transmission profile.
In known third generation CT systems, the x-ray source and the detector array are rotated with a gantry within the imaging plane and around the object to be imaged so that the angle at which the x-ray beam intersects the object constantly changes. A group of x-ray attenuation measurements, i.e., projection data, from the detector array at one gantry angle is referred to as a xe2x80x9cviewxe2x80x9d. A xe2x80x9cscanxe2x80x9d of the object comprises a set of views made at different gantry angles, or view angles, during one revolution of the x-ray source and detector.
In an axial scan, the projection data is processed to construct an image that corresponds to a two dimensional slice taken through the object. One method for reconstructing an image from a set of projection data is referred to in the art as the filtered back projection technique. This process converts the attenuation measurements from a scan into integers called xe2x80x9cCT numbersxe2x80x9d or xe2x80x9cHounsfield unitsxe2x80x9d, which are used to control the brightness of a corresponding pixel on a cathode ray tube display.
In at least one known imaging system, a single scout image is generated by fixing the position of the x-ray source and translating the object in a z-axis direction. As a result, the scout image is similar to a plain radiography image. Using the scout image, an operator may identify anatomical landmarks so that proper techniques may be selected for different areas of the object. However, as a result of generating the scout image from a single projection angle, no depth information regarding the object anatomy is provided.
It is therefore seen to be desirable to provide a CT system which provides scout images having depth information of the object. It is also desirable to generate a shaded 3D image of the scanned object.
There is therefore provided, in one embodiment of the present invention, a method for generating depth information images of an object using a computed tomography system by performing multiple scout scans of the object, generating a scout image for each scout scan, and displaying the scout images from each scout scan at least once.
The above described embodiment and others described herein generate scout images having depth information of anatomical objects. In addition, 3D images are rapidly generated without increasing the cost of the system.